Power generating devices that harvest energy from natural environments are widely researched and devices that provide “free” energy are always desired. The concept and technology for generating electrical power from vibrating piezoelectric (“piezo”) cantilever beams is known and is in use for power harvesting in vibrating environments. In these devices, an array of piezo cantilever beams is fabricated on a substrate, usually using thin film micro-electromechanical systems (“MEMS”) processes, and a small proof mass is deposited or otherwise attached to the free end of each beam. As the device holding the substrate vibrates, the cantilevers start vibrating at their natural frequency (resonate) with the proof mass being the element that induces the bending force on the beam. The piezo cantilever beams are constructed in a way that when they bend, an electrical voltage is generated between the top and bottom surfaces, and when connected to an electrical circuit, electrical current develops. Such devices use vibration from the environment as their energy source and the magnitude of the cantilevers' bending and electrical energy produced is limited by the energy in this vibration and the geometry of the beams, mainly their cross section and weight of proof mass. Since in most cases of energy harvesting from vibration, the available energy is not very high and since the proof mass (comparing to the stiffness of the beams) is not large, the bending of the piezo beams is small and the amount of energy produced is also not high.
Power generation using compressed air is also a known technique. Typical air pressure power generators use the air's kinetic energy as a means to rotate some kind of turbine that in turn rotates an electromagnetic generator. This kind of air pressure generators require high pressure levels and are relatively big and heavy. They also have inherent startup losses due to the need to accelerate the moving masses before power is generated.
In the area of actuating devices, or actuators, for some MEMS based applications such as fluidic microchannel chip cooling devices, a high-force, large-stroke high-frequency actuator is required. Current actuators in the MEMS world do not meet these three high performance requirements. As a result the desired performance of the device cannot be met.
There are several MEMS based linear actuator technologies. The most common one is the electrostatic comb-drive actuator that delivers large-stroke actuation at high frequencies but with limited force and with limitations on its size that reduce scalability potential to larger force actuators. On the other side of the spectrum is the thermal actuator that delivers large stroke and high force at a very low frequency. Other actuation technologies include stacked piezo layers (high force and frequency and very small stroke. Not really a MEMS actuator), Piezo membrane (high force and small stroke) and others. None of the existing known actuators deliver the combination of these three performance characteristics.
While the prior art techniques may prove suitable for certain intended uses, for other applications such techniques can be subject to limitations.